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s HEIMANN ELECTRODE FOR ELECTRIC ARC LAMPS.

No. 498,915. Patented June 6,1893.

WITNESSES. V lNVENTOH' 9 J %Wm WW 9 BY kwpm m,

UNITED STATES PATENT OFFICE.

SALOMON HEIMANN, OF NEW YORK, N. Y.

ELECTRODE FOR ELECTRIC-ARC LAM PS.

SPECIFICATION forming part of Letters Patent N 0. 498,915, dated June 6,1893.

Application filed October 24, 1892.

To aZZ whom it may concern.-

Be it known that I, SALOMON HEIMANN, a citizen of Germany, residing inthe city of New York, in the county of New York and State of New York,have invented certain new and useful Improvements in Electrodes forElectric-Arc Lamps, of which the following is a specification.

The object of my invention is to treat carbons for electric arc lamps insuch a manner as to prevent the rapid consumption of the carbons by thelight are and the influence of the atmosphere; and the inventionconsists in a carbon provided with a coating of a mixture of powderedcalcined soapstone, Waterglass and oil and lamp-black in proportionsthat will be set forth hereinafter.

In the accompanying drawing, a longitudinal sectional view of myimproved carbon is shown.

The carbon A, which may have any desired dimensions, is provided with acoating a of refractory materiahwhich coating has a thickness of aboutone sixty-fourth to one thirtysecond of an inch, so as not to interferewith the easy movement of the carbon in passing through apertures inguard-plates, reflectors, &c. This coating is preferably made of thefollowing mixture: seventy parts by weight of powdered calcinedsoapstone, five parts by weight of water-glass, twenty parts by weightof oil and five parts of lamp black. These materials arethoroughlyground together and mixed with enough Water to give them aboutthe consistencyof cream. The carbon is then dipped into the same until acoating adheres Serial No. 449,775- (No model.)

to the same of from about one sixty-fourth to one thirty-second of aninch in thickness, and then the carbon is dried for one or two days.This coating is refractory and protects the carbon from the influencesof the atmosphere and the light arc, except at the point of the are.

I am aware that carbons in electric lamps have been provided with acoating of plaster of paris, for example, the well known Jablochkofi":candle, and that carbons and filaments have been coated with enamel,glass, clay, 650., but these differ totally from my improved carbon, asthe coating of myim proved carbon is very thin and can crumble away atthe point of the are as the carbon is consumed, and thus prevents theformation of craters, and protuberances which are so very objectionablein arc lamps; but at the same time this improved coating fully protectsthe carbon from the influence of the atmosphere and the electric lightare.

Having thus described my invention, I claim as new, and desire to secureby Letters Patent- An electric are light carbon, provided with arefractory coating composed of a mixture of calcined soapstone,Water-glass, oil and lamp-black about in the proportions given.

In testimony that I claim the foregoing as my invention I have signedmyname in presence of two subscribing witnesses.

SALOMON HEIMANN.

Witnesses:

OSCAR F. GUNZ, CHARLES SoHRonDER.

